A method and a system including programmed general purpose digital computers on a computer network for effectuating the real-time trading of a commodity including, but not limited to, a currency. A commodity trading method implemented at a client or trader computer connected to a computer network (e.g., the Internet) includes (a) receiving, in encoded form via a computer network, a plurality of bids and a plurality of offers pertaining to a common commodity, (b) displaying the bids and offers on a computer monitor, (c) generating a trading offer including a trading rate or price per unit of the commodity and a number of units of the commodity, (d) automatically calculating a total stop amount for the trading offer, (e) automatically or electronically comparing the total stop amount with an amount in a client or trader account, and (f) transmitting a digital signal encoding the trading offer to multiple other clients via the computer network upon and only upon a determination that the total stop amount is less than an amount in the client account.